Henri Samuli Seppälä (born June 7, 1980 in Espoo, Finland), better known as Henkka T. Blacksmith, is the bassist of the Finnish metal band Children of Bodom. Henkka is also responsible for backing vocals, both live and in the studio. "Henkka" is a very common nickname for "Henri", and "seppä" means "blacksmith" in English. The "T." in the middle of his name stands for "Torso", another of his nicknames.

Henkka first started playing guitar at the age of eleven. He got into the heavy metal scene through his brother, who listened to bands such as Slayer and Pantera with his friends. Before that, he had only had contact with rock 'n' roll and glam bands such as Guns N' Roses and Poison. As time passed, his interest started leaning towards heavier bands, until in the early 90s he discovered black metal and death metal bands such as Burzum, Dissection and Cannibal Corpse.

He played in his first band at the age of 13. It was called Aivokasvain (Brain Tumour). He was part of the band for two years, and then quit, switching his main instrument to the bass.

When Samuli Miettinen quit Inearthed (the original name of Children Of Bodom) in 1996, Henkka joined the band, asked by lead guitarist/singer Alexi Laiho, adopting the 5-string bass.

He is the frontman of the band when it comes to interviews and public appearances. Other than the fact that he can speak Finnish, English, Swedish and some French, he is also the most equilibrated member of the band, in a general way.

He studies political science and political history at the University of Helsinki when he has time, which is not too often. He is also into sports and has a passion for football, however he also enjoys swimming. Henkka is completely dedicated to Children of Bodom, and doesn't have any side-project. According to him, the most important things in his life are his family and his band.